This invention relates to magnetic transducing head assemblies, and particularly to such assemblies requiring that one or more heads to precisely mounted to fine tolerances in two or three orthogonal directions.
In the magnetic tape recording and reproducing art, it is frequently desired to mount the magnetic transducing heads (i.e., record heads, read or playback heads, and erase heads) on a rotating drum for successive sweeping motion across the tape, either nearly transversely, or obliquely as in helical-scan machines. It has always been a problem in such machines to achieve precisely uniform circumferential spacing between the heads, as well as precise radial and axial positioning. An elaboration of this problem is that of achieving such precision in what is termed "field-replaceable" heads, so that the entire drum assembly does not have to be returned to the factory for the replacement of a single head. Ideally, it ought to be possible to send a new head from the factory, or to maintain a reserve stock of such heads in the field, for instant interchange with defective heads on the drum, the defective heads being then returned to the factory for repair. An example of one solution to this problem is disclosed in co-pending U.S. patent application Ser. No. 729,283, now U.S. Pat. No. 4,099,212, entitled "Rotating Transducing Head Assembly," filed Oct. 4, 1976 by the present inventor.
The field-replacement problem is further complicated when it arises in connection with so-called "bi-morph" or "automatic scan-tracking" heads, such as those disclosed in co-pending U.S. patent applications Ser. No. 668,651, now U.S. Pat. No. 4,151,569, entitled "Positionable Transducer Mounting Structure," filed Mar. 19, 1976, by Richard Allen Hathaway, Ser. No. 677,683, now U.S. Pat. No. 4,093,885, "Transducer Assembly Vibration Sensor," filed Apr. 19, 1976 by David E. Brown (continuation-in-part of Ser. No. 668,653 filed Mar. 19, 1976), and Ser. No. 722,822, now U.S. Pat. No. 4,099,211, "Positionable Transducing Mounting Structure and Driving System Therefor," Richard A. Hathaway, filed Sept. 13, 1976. In such head assemblies, the head is mounted at the extremity of a thin leaf member, which is displaceable laterally of the tracking direction as the drum rotates across the tape, so as to be able to follow, on playback, a track that, for any of several possible reasons, does not conform to a normal shape.
In the present invention, it is desired to use such an automatic scan tracking head as merely one of six heads on the same drum, the other five being of fixed-head types, i.e., fixed with respect to the drum. The problem then becomes one of making all six heads, though of different types, field-replaceable in a simple and uniform way.
Accordingly, it is an object of the present invention to provide a precision-mounted field replaceable head assembly for rotating transducing head drums, suitable for use with a variety of different head types.